Control valve with inherent circuit protection



June 14, 1955 R. F. HODGSON CONTROL VALVE WITH INHERENT CIRCUITPROTECTION Filed Oct. 11, 1954 2 Sheets-Sheet l R 055% Go o wuBwwm/Mm wm m B m V m 3 m 5 8 m mm 4% NH om 5 mm 3 ,ww Nm Wm m m m 5 0 @N 5 l v ya m m m w v mm 3 N m -1 2 m Em H.-- m d .iititii 1E a \x 5 mm mm N H m2m3 mfi m4 P w w 2 main 0E 06' Roberc F Hodgs on BY M34 ATTORNEYS June 4,1955 R. F. HODGSON CONTROL VALVE WITH INHERENT CIRCUIT PROTECTION 2Sheets-Sheet 2.

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1N VENTOR Roberi: F; Hoclgson R MN i ATTORNEYS 2,710,628 Patented June14, 1955 CONTRQL VALVE WITH INHERENT CIRCUIT PROTECTION Robert F.Hodgson, Chagrin Falls, Ohio, assignor to The New York Air BrakeCompany, a corporation of New Jersey Appiication fictober 11, 1954,Serial No. 461,428

6 claims. (cl. 137*622) This invention relates to control valves forhydraulic and similar pressure motors, particularly double-actingmotors.

The patent to Kirkham 2,608,824, September 2, 1952,. relates to a flowcontrol valve for double-acting motors which controls the exhaust flowsfrom either end of a double-acting motor in response to the supply flowto the opposite end of that same motor. If the supply pressure to oneend of the double-acting cylinder falls or if the load reverses, theKirkham device close-s or throttles appropriately the exhaust path fromthe other end of the cylinder. This is complementary to the protectionoffered by schemes which interpose check valves in the supply path, andthe Kirkham patent shows such a check valve in the valve plunger.

The patent to Stephens 2,359,802, October '10, 1944, describes a controlvalve having a hollow plunger with lateral ports and at least one checkvalve in the bore of the plunger serving to control flows through thebore between certain of the lateral ports. One of these is supply flow.The valve is simple to construct and can be designed to suit the portingof particular seats. Its great advantage however is that it affordsflexibility in design, since mere substitution of a hollow valve withone or two check valves, in an existing seat can afford new or improvedfunctions as compared to the same seat with some other more conventionalvalve. It is economically advantageous to standardize the seat componentof a valve (which is permanently connected in the circuit), and vary theover-all characteristics by selection of differently ported plungers.The Stephens invention has gone into extensive commercial use because ofthis desirable characteristic. 1

.The present invention has the effect of introducing functions similarto those of the Kirkham device into a hollow plunger While retaining thecheck-valve effect characteristic of the Stephens invention. Thus,without functional sacrifice, and with actual saving in the cost ofmanufacture, the advantages of two diverse valve mechanisms are combinedand are rendered readily available in an interchangeable plunger.Indeed, there is a functional advance over the Kirkham concept, becauseboth inlet and exhaust flows are controlled simultaneously andindependently by the two flow control valves which, according to thepresent invention, are mounted in the bore of a hollow plunger.

Referring to the preferred embodiment of the concept, a hollow plungerhas the middle portion of its bore obstructed by an open-ended cylinderin which a closely fitted axially shiftable piston Works. At each end ofthis cylinder the plunger has a larger bore, each such larger boreserving as a cylinder and as a guide for the corresponding one of twopiston-actuated piston-type flow control valves. Each of these lastnamed valves controls ports leading through the walls of the plunger,and serves as a flow-control valve. Each also performs the functions ofStephens check valve, though neither takes the form of a conventionalcheck valve.

The axially shiftable piston closes the bore of the openended cylinder,so that this can never short circuit supply to discharge. In each activeposition the piston serves as a force-transmitter, enabling supplypressure to react simultaneously upon both the flow-control valves. Thereaction is direct in the case of a selected one of the valves and isexerted through the piston in the case of the one not so selected. Theselection depends on the direction in which the plunger is shifted fromits mid-position.

"'- The open-ended cylinder is arranged to serve also as stops for theflow-control valves, which engage it in their portclosing positions.

The invention will now be described by reference to the accompanyingdrawings which illustrate how the improved plunger can be assembled witha conventional valve body.

Figure 1 is an axial section through the body of a two-plunger valve ofthe series connected type. In this view the two valve seat bores areidentically ported. Both valves are in hold position (open center), theupper one being a conventional Stephens valve for a singleactingcylinder and the lower one embodying the invention and adapted tocontrol a double-acting cylinder.

Figure 2 is a fragmentary view similar to a portion of Figure l, butshowing the lower valve of Figure l shifted to the right.

Figure 3 is a fragmentary section on the line 3-- of Figure l.

Figure 4 is a side elevation of one of the fiowcontrol valve units.

Figure 5 is an axial section of a modified plunger.

All statements of direction refer to Figure 1.

Valves of the type here indicated are commonly used with a constantlyrunning pump which draws oil from a sump and delivers it under pressureto the inlet of the valve, which in turn discharges spent oil to thesump. Hence on Figure l the valve inlet is indicated by the legend Highpressure oil from pump and the'valve discharge by the legend To sumpf.The connections to the motor cylinders are not elaborated in thedrawings, but the communicating seat ports are adequately identi fied.

Since the valve is of the series-connected open-center type, the pump isunloaded through the valve when both plungers are in hold position(shown in Figure 1). hold position in a double-acting motor is one inwhich both motor ports are closed.

'- The valve housing conforms generally to known practice and comprisesa body 6 and a cap 7 held together by screws 8 (one only of these screwsis indicated by broken lines.) The cap is sealed to the body by-gasket9. The body has two identical parallel bores-11 and 111 in which theports are bore-encircling grooves.

To save repetition all identified features of bore ill which areidentical with those of bore ll will be given the same referencenumerals increased by 100.

At mid-length, bore 11 has an encircling groove 12, which is thedischarge port. At either side of groove 12 are encircling grooves 13which are supply ports. These are fed through a branching passage 14which leads from the supply connection 15. Since the valve is of theseries connected type discharge port 12 feeds the supply ports 113 ofbore Iii through a branching passage 114i.

' The discharge port groove 112 of bore 111 leads to dischargeconnection 16 as do two branches l7 and 18. Branch 17 connects withexhaust grooves 19 and 119. Branch 18 connects with space 21 within cap7 into which space the ends of both plungers project, space 21functioning as an exhaust port as will be explained.

I The groove ports 22 and 23 are motor ports, that is,

they are connected to opposite working spaces of adouble-acting cylinderor other motor unit. All ports in 3 bore 11 are controlled by a plunger24 in which the novel features of the invention are incorporated.

Ports in bore 111 are controlled by a plunger 25 constructed accordingto the disclosure of Stephens patent, above identified. Since plunger 25is designed to control a single-acting motor the connection to port 122is plugged and port 123 is connected to the working space of the motor.If it be desired to control a double-acting motor ports 122 and 123 areconnected to the opposite working spaces thereof and an appropriateplunger is substituted for plunger 25.

Since the bores 11 and 111 are identical as to size and port location,Figure 1 demonstrates the possibility of applying the invention bymerely substituting the newly devised plunger.

Plunger 24 is basically a tube which makes a close working fit in bore11, is sealed by an O-ring 25 where it emerges from the bore, and isclosed at its end by plugs 27 threaded into its ends. These plugs areidentical except that the right hand one carries a clevis 28 forconnection of the valve-actuating linkage (not shown). Each plug issealed by an O-ring 29 and carries on its inner end a cup-like extension31 which serves as a valve stop and also as a seat for a valve-loadingspring.

The plunger valve is of the open center type, i. e., it connects ports12 and 13 in mid-position and disconnects them when displaced in eitherdirection therefrom. There are various known portings to afford thesefunctions, but the simplest, and the one best adapted to the presentinvention, comprises two encircling grooves 32 with a narrow interveningland 33.

Within land 33 and grooves 32 the bore of plunger 24 receives a tightlyfitted plug 34 with an open ended mial bore. Within this bore a floatingpiston 35 is reciprocable. The ends of the plug serve as stops opposedto corresponding stops 31, so that the range of motion of theflow-control valves (later to be described) is defined. The function offloating piston 35 is to open selectively the flow control valve on theexhaust side and at the same time alford no short circuit path betweenports 12 and 13.

To atford the desired result the left-handgroove 32 is connected to thespace at the right end of floating piston 35 and the right-hand groove32 is connected to the space at the left-hand end of the piston. In theconstruction shown in Figures l3 this is done by cutting grooves 36, 37from opposite end of plug 34 long enough to reach radial ports 38, 39.

A somewhat more expensive construction is shown in It requires that theplunger be bored from Figure 5. each end so as to leave an integralcentral portion replac Reverting to Figures l-3, beyond each end of plug34 ports 43, 44 are drilled through the plunger. They are slightlyoffset in the direction of the axis for graduation purposes. Nearer eachend of the plunger are drilled ports 45. The ports above named areterminal portions of flow-paths through portions of the bore of theplunger. For example, in Figure 2 supply flow is controlled by the leftportion of plunger 24 from 13, through 43, 44, through the plunger bore,through 45 to motor port 23. In the same figure exhaust flow from theother motor port is controlled by the right portion of plunger 24 and isfrom 22 through 43, 44, dirough the plunger bore through 45 to 19 and sovia 17 to sump.

These flows are controlled according to the invention by identicalpressure-actuated balanced piston valves generally indicated by thenumerals 46 and 47. A description of the left-hand one in Figure 1 willsuflice for both, it being understood that they are reversely arrangedand biased toward each other by the springs 48.

As best shown in Figure 4, the valve proper is a cup shaped piston headhaving two narrow lands 49 between which are vent holes 51. These permitthe valves to reach the positions shown in Figure 2 without becomingoilbound. At that point the stop flanges 31 arrest them. A slender stem52 connects the valve head with an actuating piston 53. These headsengage the opposite ends of plug 34 and piston 35 and define the closedpositions of the valves.

As is illustrated in Figure 2, when the plunger 24 is shifted to chargeone motor working space and vent the other, supply pressure actsdirectly on the pistonhead 53 of that valve which controls supply flow(valve 46 in Figure 2), but acts through piston 35 on that valve whichcontrols exhaust flow (valve 47 in Figure 2).

These valves 46 and 47 are not check valves in the true sense, but theyaccomplish all the functions of Stephens check valve and additionalfunctions. If supply pressure in passage 14 falls from any cause whilethe plunger is away from its mid-position (hold position) both valves 46and 47 moves in closing directions and either throttle both supply andexhaust flows or close them off altogether. If they close they establisha hold position irrespective of the position of plunger 24.

The plunger 24 is held yieldingly in mid-position by a centering spring54 (see Figure 2) which encloses a sleeve 55 slidable between theflanged rings 56 and 57. One flange on each ring engages a groove 58surrounding plunger 24 near its left-hand end. Such centering springsare well known in the art and an identical one is shown on theconventional plunger 25.

Plunger 25 being conventional requires no description. It merelyillustrates the prior art and emphasizes the point that a plunger suchas 24 can be substituted in bore 111 and can then afford additionalfunctions and safeguards. This presupposes that the connection to port122 is unplugged and a double-acting motor is connected to the two ports122, 123.

The construction of the best embodiment presently known has beendescribed in detail to comply with the statute. Structural changeswithin the scope of the claims are contemplated and are not excluded byimplication.

What is claimed is:

1. For use in a valve housing having a bore with spaced supply anddischarge and motor ports; a plunger valve comprising a tubular elementshiftable in said bore and having spaced lateral ports so located thatin three different positions the plunger alternatively closes a motorport, or connects Lhat port selectively with supply or with exhaust bypaths leading through the bore of the tubular element between spacedlateral ports at least one of which ports is common in both paths; apiston valve controlling the lateral port just specified and thuscontrolling both flow paths said valve being balanced so as to beindifferent to the pressure of fluid flowing through said paths; meansbiasing said balanced valve in its closing direction; pressure motormeans for opening said valve; and port means effective in bothconnecting positions of the plunger to subject said motor means tosupply pressure, and effective in the other position to vent said motormeans.

2. The combination of a valve body having a seat comprising a bore withsupply and discharge ports near mid-length of the bore, discharge portsadjacent the end of the bore and two motor ports, each located between asupply port and a corresponding end discharge port; a valve plungeraxially shiftable in said bore and having ports which in themid-position of the valve plunger connect the first named supply anddischarge ports, opposite end portions of said valve plunger beingtubular and each having lateral through-ports which are blanked in themid-position of the valve plunger, and which according as the valveplunger is displaced in one or the other direc tion from mid-positionafford simultaneous flow paths through respective tubular portions fromsupply to a selected one of said two motor ports and from the other oneof said motor ports to an end discharge port; flow control valves, oneshiftable in each tubular portion and each controlling inter-port flowtherethrough; means biasing said flow control valves to close; pressuremotor means mounted in said valve plunger and at least partly in saidtubular portions, and operable by fluid pressure to move said flowcontrol valves in their opening directions; and means rendered effectiveby shift of said valve plunger from its mid-position to subject saidpressure motor means to supply pressure.

3. The combination of a valve body having a seat comprising a bore withsupply and discharge ports near mid-length of the bore, discharge portsone adjacent each end of the bore and two motor ports, each located between a supply port and a corresponding end discharge port; a valveplunger axially shiftable in said bore and having ports which in themid-position of the valve plunger connect the first named supply anddischarge ports, opposite end portions of said valve plunger beingtubular and each having lateral through-ports which are blanked in themid-position of the valve plunger, and which according as the valveplunger is displaced in one or the other direction from midpositionafford simultaneous flow paths through respective tubular portions fromsupply to a selected one of said two motor ports and from the other oneof said motor ports to an end discharge port; flow control valves, oneshiftable in each tubular portion and each controlling inter-port flowtherethrough, each of said flow control valves being of the balancedpiston type and indifferent to the pressure of fluid flowing through thecorresponding tubular portion; means biasing said flow-control valves toclose; pressure motor means mounted in said valve plunger and at leastpartly in said tubular portions, and operable by fluid pressure to movesaid flow control valves in their opening directions; and means renderedeffective by shift of said valve plunger from its mid-position tosubject said pressure motor means to supply pressure.

4. The combination of a valve body having a seat comprising a bore withsupply and discharge ports near mid-length of the bore, discharge portsone adjacent each end of the bore and two motor ports, each locatedbetween a supply port and a corresponding end discharge port; a valveplunger axially shiftable in said bore and having ports which in themid-position of the valve plunger connect the first named supply anddischarge ports, opposite end portions of said valve plunger beingtubular and each having lateral through-ports which are blanked in themid-position of the valve plunger, and which according as the valveplunger is displaced in one or the other direction from mid-positionafford simultaneous flow paths through respective tubular portions fromsupply to a selected one of said two motor ports and from the other oneof said motor ports to an end discharge port; flow control valves, oneshiftable in each tubular portion and each controlling inter-port flowtherethrough; means biasing said flow control valves to close; meansaflording within the valve plunger an open ended cylinder with its axissubstantially parallel with the valve plunger axis, and its endscommunicating with respec tive tubular end portions of the valveplunger; a floating piston in the bore of said cylinder; actuatingpistons in said tubular end portions in position to be engaged by saidfloating piston and each connected with a corre: sponding flow controlvalve; and port means rendered effective selectively by motion of thevalve plunger in respective directions from its mid-position to admitsupply pressure fluid between a selected actuating piston and theadjacent end of the floating piston.

5. A plunger valve comprising a tubular element; a floating pistonaxially shiftable in the bore of said tubular element substantially atmid-length thereof, and dividing said bore into two non-communicatingportions, each portion having spaced lateral ports which afford distinctflow-paths, one through the bore of each portion; two piston valves eachvalve controlling flow through a corresponding one of said flow paths;yielding means biasing each of said piston valves toward said floatingpiston; two piston heads each for actuating a corresponding piston valvein opposition to its biasing means and each interposed in said borebetween its piston valve and the proximate end of said floating piston;motion limiting means for said valves and piston heads; and meansaflording two distinct ports each leading to the space between acorresponding end of the floating piston and the adjacent piston head.

6. The combination defined in claim 5 in which each piston head and itscorresponding piston valve are connected together to form a unitbalanced so as to be indifferent to the pressure of fluid whose flow thepiston valve controls.

No references cited.

